To sustain their growth and reproduction, parasites exhibit distinct adaptations that allow them to acquire nutrients unidirectionally from the host. An example par excellence is the heme acquisition pathway exploited by trypanosomatid and helminth parasites - initially discovered in the genetically tractable roundworm C. elegans. Using C. elegans, the PI recently identified the HRG-1 family of proteins, the first bona fide metazoan heme importers/transporters. Currently there are no pharmacological tools to aid in the study of the cellular and physiological roles of metazoan heme transporters. Here, we propose the development and validation of a cell-based, HTS-compatible screen for small molecule antagonists of a prototypical C. elegans heme transporter expressed in yeast using a simple growth assay. Preliminary low-throughput assays suggest that this approach is feasible for conversion to an HTS format. A powerful combination of in vitro, cell-based, and physiological assays are also in place to confirm and prioritize compounds identified in this manner. Successful execution of this proposal will require the collaboration of two researchers having expertise in the molecular target of interest and HTS development. It is anticipated that reagents identified in this screen will ultimately be used to establish the feasibility of targeting this pathway for the treatment of helminth infections, Trypanosomiasis, intestinal nematodes, kinetoplastid diseases, lymphatic filariasis, onchocerciasis, and Leishmaniasis, as well as human genetic disorders of heme and iron metabolism. The exploration of new selective targets for the treatment of such diseases is of particular interest as most drugs currently in use are either prohibitively expensive, have high toxicity, or have already promoted the development of resistant strains of parasites. PUBLIC HEALTH RELEVANCE: We propose to develop an assay for high-throughput screening of small molecule antagonists of a heme transporter. The study of heme trafficking has great importance for the treatment of human iron deficiency, one of the top ten mortality factors worldwide, and for combating human and agricultural parasites. These studies will be greatly facilitated by the identification of such interfering ligands, none of which currently exist for these targets.